Glycerophospholipid metabolism in the brain will be studied. Properties of phosphotransferases for the synthesis of choline and ethanolamine glycerophospholipids will be determined and compared with enzymes in liver. Ethanolamine phosphotransferase and choline phosphotransferase will be separated, solubilized, and purified if possible with improved assay procedures. Properties of these enzymes will be determined in neuronalperikarya, astroglia, and oligodendroglia during rabbit brain development. Topological locations of ethanolamine phospholipids will be determined in microsomes and plasma membranes. High performance liquid chromatographic procedures will be developed for separation of lipid classes from brain and then for the separation of all molecular species will be used for metabolic studies. Pathways for synthesis of plasmalogens from labeled precursors will be studied in brain after intracerebral injection, in C6 glial cells in culture, and with microsomes. All classes of plasmalogens will be studied. Improved assay procedures will be developed for plasmalogenase, diacylglycerol lipase, and monoacylglycerol lipase. These enzymes and phospholipase A1 and A2 will be purified from brain and characterized, particularly for location and effects of Ca2 ion. Cultured cells will be used for further studies of phospholipases acting on exogenous glycerophospholipids.